Grape seed extract prevents chlorpyrifos-induced toxicity in rat liver through the modulation of phase I detoxification pathway.

Chlorpyrifos (CPF) poisoning is a public health problem for which there is not currently any effective prophylaxis. In this study, we investigated the protective effect of grape seed extract (GSE) against CPF-induced hepatotoxicity. Rats were daily treated either with CPF (2 mg/kg) or CPF and GSE (20 mg/kg) for 1 week, sacrificed, and their livers dissected for biochemical, molecular, and histopathological analyses. CPF generated liver dysfunction by altering carbohydrate, lipid, amino acid, ammonia and urea metabolism, and provoked mitochondrial impairment through disturbing tricarboxylic acid (TCA) cycle, oxidative phosphorylation (OXPHOS), and mitochondrial viability. CPF also induced cholinergic excitotoxicity along with oxidative stress and histopathological alterations. Interestingly, treatment with GSE prevented all the detrimental effects of CPF through the regulation of cytochrome P450 (CYP450) gene expression. Molecular docking analysis indicated that GSE-containing polyphenols acted as epigenetic modulators through inhibiting DNA (cytosine-5)-methyltransferase 1 (DNMT1), thus favoring the CYP2C6 detoxification pathway. Thereby, GSE might be a promising strategy in the protection of the liver against CPF toxicity.

Effects of grapeseed extract on doxorubicin-induced cardiotoxicity in rats.

BACKGROUND: Doxorubicin (DX) is used for the treatment of many types of cancer; however, a side effect of this agent is cardiotoxicity, which may lead to cardiomyopathy or cardiac failure. Oxidative stress is thought to play a major role in the development of cardiotoxic effects. Proanthocyanidins found in grapeseed (GS) extract may inhibit chemically induced lipid peroxidation and apoptosis caused by oxidative stress. We aimed to investigate the cardioprotective effects of GS extract against DX-induced cardiotoxicity. METHODS: A total of 28 male Sprague Dawley rats were grouped to receive: (a) standard nutrition (n = 7); (b) standard nutrition with an additional dose of 10 mg/kg DX (n = 7); (c) standard nutrition plus 100 mg/kg/day of GS (n = 7); (d) standard nutrition with 100 mg/kg/day of GS plus a single dose of 10 mg/kg DX. After 35 days the rats were decapitated and blood samples were taken for biochemical testing. Cardiac tissue samples were prepared for microscopy and histopathological evaluation. RESULTS: Rats in the DX group exhibited significant elevations in biomarkers such as troponin and NT-proBNP as well as in oxidative stress markers compared with all other groups. Histopathological examination corroborated these findings by demonstrating significant and severe structural injury in the cardiac tissue of DX rates. Moreover, rats in the DX + GS group had significantly lower cardiac injury than rats in the DX group according to both biochemical (troponin and NT-proBNP) and histopathological analyses. Serum malondialdehyde levels (a marker of oxidative stress) in the DX + GS rats were significantly lower than in the DX rats. CONCLUSION: Our findings suggest that GS may reduce the severity of DX-induced cardiotoxicity and thus has the potential to prevent cardiac injury in this setting.

Utilization of plant-based protein-polyphenol complexes to form and stabilize emulsions: Pea proteins and grape seed proanthocyanidins.

Plant-based proteins and polyphenols are increasingly being explored as functional food ingredients. Colloidal complexes were prepared from pea protein (PP) and grape seed proanthocyanidin (GSP) and the ability of the PP/GSP complexes to form and stabilize oil-in-water emulsions were investigated. The main interactions between PP and GSP were hydrogen bonding. The stability of PP-GSP complexes to environmental changes were studied: pH (2-9); ion strength (0-0.3 M); and temperature (30-90 °C). Emulsions produced using PP-GSP complexes as emulsifiers had small mean droplet diameters (~200 nm) and strongly negative surface potentials (~-60 mV). Compared to PP alone, PP-GSP complexes slightly decreased the isoelectric point, thermostability, and salt stability of the emulsions, but increased their storage stability. The presence of GSP gave the emulsions a strong salmon (red-yellow) color, which may be beneficial for some specific applications. These results may assist in the creation of more efficacious food-based strategies for delivering proanthocyanidins.

Effects of grape seed extract on performance, immunity, antioxidant capacity, and meat quality in Pekin ducks.

This study was conducted to evaluate the effects of grape seed extract (GSE) on growth performance, immunity, antioxidant capacity, relative organ weight, jejunum morphology, ileal microflora, and meat quality in Pekin ducks. A total of 1,500 female 1-day-old Pekin ducklings (52.0 ± 0.2 g) were blocked based on body weight (BW) and randomly allocated into 3 treatments with 10 replicates of 50 birds each. The experiment lasted for 6 wk, and dietary treatments included corn-soybean meal-based diet supplemented with 0, 0.01, and 0.02% GSE. The supplementation of GSE increased (P < 0.05) body weight gain (BWG) and final BW linearly but decreased (P < 0.05) feed-to-gain ratio (F/G) linearly during day (D) 22 to 42 and the entire experiment. The inclusion of GSE increased (P < 0.05) serum superoxide dismutase, glutathione peroxidase, total antioxidative capacity, catalase, complement4, immunoglobin G, interleukin-2, and interferon-γ linearly but decreased (P < 0.05) serum malondialdehyde linearly. The relative weight of carcass, breast meat, and spleen in GSE treatments was increased (P < 0.05) linearly, whereas the relative weight of abdominal fat was decreased linearly (P < 0.05). Birds fed GSE1 and GSE2 diets had lower (P < 0.05) cook loss, 2-thiobarbituric acid reactive substances, and drip loss on day 3 and 5 linearly but higher (P < 0.05) pH24h and water-holding capacity. The addition of GSE decreased (P < 0.05) jejunum crypt depth and ileal Escherichia coli counts linearly but increased (P < 0.05) jejunum villus height: crypt depth ratio and ileal Lactobacilli linearly. Taken together, the inclusion of GSE increased final BW and BWG, decreased F/G during day 22 to 42 and day 1 to 42, partially improved antioxidant activities, immunity, meat quality, and gut health in Pekin ducks.

Molecular hybridization of grape seed extract: Synthesis, structural characterization and anti-proliferative activity in vitro.

The grape seed extract (GSE) hybridized with medium-chain saturated fatty acids (decanoic acid) exhibited higher lipophilicity, antioxidant activity, and anti-proliferative activity than its parents. The chemical structures of individual hybridized GSE derivatives were identified as 3'-O-decanoyl catechin, 3'-O-decanoyl epicatechin, 3', 5'-2-O-decanoyl epigallocatechin, and 3', 4', 3″, 5″-4-O-decanoyl epicatechin gallate by HPLC-MS2 and 1H and 13C NMR. For growth inhibitory effect on HepG2 cells, hybridized GSE derivatives (EC50 = 44.38 µg/mL) were significantly (p < 0.01) stronger than natural GSE (EC50 = 60.83 µg/mL) due to increased lipophilicity. The effects of GSE derivatives on apoptosis and cell cycle in HepG2 cells were further evaluated by flow cytometry. The results showed that the percentage of apoptotic cells increased markedly in the presence of hybridized GSE derivatives. Moreover, hybridized GSE derivatives were capable of inducing cell cycle arrest in G1 phase. This research suggests that hybridized GSE derivatives are effective lipophilic antioxidants and show the potential as adjuvant therapy for cancer.

Phenolic Metabolites in Plasma and Thigh Meat of Chickens Supplemented with Grape Byproducts.

Grape byproducts are rich sources of polyphenols with powerful antioxidant and health-promoting effects. The impact of supplementing chicken diets with grape byproducts on plasma and thigh meat concentrations of phenolic metabolites was evaluated by analyzing samples by high-performance liquid chromatography quadrupole time of flight mass spectrometry. Chickens were fed three experimental diets: Control diet, Control+8% grape pomace, and Control+0.1% grape seed extract. In plasma, 32 phenolic metabolites were identified, some of which were conjugated catechin/epicatechin metabolites exclusively identified in chickens fed diets enriched in grape byproducts. Also, these chickens showed significantly higher plasmatic concentrations of 21 phenolic metabolites. In thigh meat, 14 phenolic metabolites were identified, but no differences were found between diets. Higher plasmatic tocopherol was found when supplementing diets with grape byproducts, while no changes were observed in meat. Thus, supplementing chicken diets with grape byproducts leads to a significant increase in the circulation of phenolic metabolites and tocopherol.

Effect of grape seed extract on maternal toxicity and in utero development in mice treated with zearalenone.

The aims of this study were to determine the polyphone content of grape seed extract (GSE) and to assess their protective effects against zearalenone (ZEN)-induced maternal toxicity and in utero development defects in mice. Five groups of pregnant mice were treated orally during days 6-13 of gestation as follows: control group, corn oil as vehicle (0.1 ml/mice)-treated group, ZEN-treated group (25 mg/kg b.w), GSE-treated group (150 mg/kg b.w.), and ZEN plus GSE-treated group. All animals were sacrificed on the 19th day of gestation and samples of bone marrow were collected for the micronucleus assay. The maternal and developmental toxicity were carried out. The HPLC analyses revealed that GES is rich in gallic acid, syringic acid, vanillin, quercetin, and coumaric acid. ZEN administration resulted in severe maternal and developmental toxicity which included an increase of micronuclei formation in bone marrow, decreased maternal weight gain, and litter weight. It also induces fetal growth retardation, increased number of the aborted dams and resorbed fetuses, abnormality of fetal bone ossification, and number of fetuses with a hematoma. GSE showed positive effects on the pregnant mice and the developing fetuses. Moreover, it counteracted the detrimental effects of ZEN in dams and fetuses. It could be concluded that polyphenols in GSE are a promising candidate to protect against ZEN toxicity in highly endemic areas.

Black rhinoceros (Diceros bicornis) and domestic horse (Equus caballus) hindgut microflora demonstrate similar fermentation responses to grape seed extract supplementation in vitro.

The domestic horse is used as a nutritional model for rhinoceros maintained under human care. The validity of this model for browsing rhinoceros has been questioned due to high prevalence of iron overload disorder (IOD) in captive black rhinoceros (Diceros bicornis), which is associated with high morbidity and mortality. Iron chelators, such as tannins, are under investigation as dietary supplements to ameliorate or prevent IOD in prone species. Polyphenolic compounds variably affect microbial fermentation, so the first objective of this experiment was to evaluate the effects of grape seed extract (GSE; a concentrated source of condensed tannins; CT) on black rhinoceros hindgut fermentation. Equine nutrition knowledge is used to assess supplements for rhinoceros; therefore, the second objective was to evaluate the domestic horse model for black rhinoceros fermentation and compare fermentation responses to GSE using a continuous single-flow in vitro culture system. Two replicated continuous culture experiments were conducted using horse and black rhinoceros faeces as inoculum sources comparing four diets with increasing GSE inclusion (0.0%, 1.3%, 2.7% and 4.0% of diet dry matter). Diet and GSE polyphenolic compositions were determined, and sodium sulphite effect on neutral detergent fibre extraction of CT-containing forages was tested. Increasing GSE inclusion stimulated microbial growth and fermentation, and proportionally increased diet CT concentration and iron-binding capacity. Horse and black rhinoceros hindgut microflora nutrient digestibility and fermentation responses to GSE did not differ, and results supported equine fermentation as an adequate model for microbial fermentation in the black rhinoceros. Interpretation of these results is limited to hindgut fermentation and further research is needed to compare foregut digestibility and nutrient absorption between these two species. Supplementation of GSE in black rhinoceros diets up to 4% is unlikely to adversely affect hindgut nutrient digestibility or microbial viability and fermentation.

Effect of dietary supplementation of grape seed extract on the growth performance, lipid profile, antioxidant status and immune response of broiler chickens.

Grape seed extracts (GSE) contain several beneficial bioactive constituents; therefore, can be utilized as a potential feed additive in broiler chickens. An experiment was conducted to investigate the effect of supplementation of broiler chicken diets with GSE as a natural antioxidant at levels of 125, 250, 500, 1000 and 2000 ppm on the growth performance, serum lipid profile, liver glutathione-reduced, thigh muscle malondialdehyde and humoral immune response against Newcastle disease virus vaccines. This experiment was performed during the life-span of chickens from 0 to 42 days of age. The results of broilers fed on diet supplemented by GSE were compared with those fed on the basal diet (control) or the basal diet supplemented by butylated hydroxytoluene as a synthetic antioxidant (BHT, 125 ppm). No significant differences were observed in the growth performance, percent livability, total lipid, high and very low-density lipoprotein cholesterols when the use of GSE or BHT were compared with the control. Total cholesterol and low-density lipoprotein cholesterol were significantly decreased after intake of GSE compared with BHT in the feed diet. The glutathione-reduced level in liver tissues was significantly increased by inclusion of GSE, but not by BHT. Inclusion of GSE or BHT decreased significantly the malondialdehyde level found in meat tissue. The antibody titer against Newcastle disease virus vaccines was significantly elevated in 28 and 35-day-old broiler chickens fed with a diet supplemented with GSE or BHT, the former providing a higher response. It can be concluded that GSE can be used as an effective natural antioxidant and immunostimulant agent in broiler chicken diets, and that 125 to 250 ppm can be considered as the optimum dosage.

MicroRNA-19a/b mediates grape seed procyanidin extract-induced anti-neoplastic effects against lung cancer.

Oncomirs are microRNAs (miRNA) associated with carcinogenesis and malignant transformation. They have emerged as potential molecular targets for anti-cancer therapy. We hypothesize that grape seed procyanidin extract (GSE) exerts antineoplastic effects through modulations of oncomirs and their downstream targets. We found that GSE significantly down-regulated oncomirs miR-19a and -19b in a variety of lung neoplastic cells. GSE also increased mRNA and protein levels of insulin-like growth factor II receptor (IGF-2R) and phosphatase and tensin homolog (PTEN), both predicted targets of miR-19a and -19b. Furthermore, GSE significantly increased PTEN activity and decreased AKT phosphorylation in A549 cells. Transfection of miR-19a and -19b mimics reversed the up-regulations of IGF2R and PTEN gene expression and abrogated the GSE induced anti-proliferative response. Additionally, oral administration of leucoselect phytosome, comprised of standardized grape seed oligomeric procyanidins complexed with soy phospholipids, to athymic nude mice via gavage, significantly down-regulated miR-19a, -19b and the miR-17-92 cluster host gene (MIR17HG) expressions, increased IGF-2R, PTEN, decreased phosphorylated-AKT in A549 xenograft tumors, and markedly inhibited tumor growth. To confirm the absorption of orally administered GSE, plasma procyanidin B1 levels, between 60 and 90 min after gavage of leucoselect phytosome (400 mg/kg), were measured by LC/MS at week 2 and 8 of treatment; the estimated concentration that was associated with 50% growth inhibition (IC50) (1.3 µg/mL) in vitro was much higher than the IC50 (0.032-0.13 µg/ml) observed in vivo. Our findings reveal novel antineoplastic mechanisms by GSE and support the clinical translation of leucoselect phytosome as an anti-neoplastic and chemopreventive agent for lung cancer.

Influence of solvents on the composition of condensed tannins in grape pomace seed extracts.

The extracting effectiveness of some solvents (water, ethanol, acetone, ethyl acetate), used as pure or in binary and ternary mixtures, was studied for the extraction of seeds from the fermented pomace of Nebbiolo cv. The aqueous mixtures of acetone provided the highest extraction yields in total polyphenols and total flavonoids. Polyphenolic extracts were also obtained with aqueous mixtures of ethanol or acetone at variable concentrations, and the condensed tannins were quantified with the phloroglucinolysis method. The aqueous mixtures of acetone were more effective than the corresponding aqueous mixtures of ethanol. The solvent influenced the extraction yield and the composition of the extracts: with the increase of the yield, the mean degree of polymerization (mDP) of the condensed tannins increased. A significant correlation was noticed between mDP and the molar percentages of (+)-catechin as terminal unit (negative correlation), and of (-)-epicatechin and (-)-epicatechin-3O-gallate as extension units (positive correlation).

Lack of tissue accumulation of grape seed flavanols after daily long-term administration in healthy and cafeteria-diet obese rats.

After ingestion flavanols are metabolized by phase-II enzymes and the microbiota and are distributed throughout the body depending on several factors. Herein we aim to evaluate whether flavanols are tissue-accumulated after the long-term administration of a grape seed polyphenol extract (GSPE) in rats and to study if compounds present in tissues differ in a cafeteria-diet obesity state. For that, plasma, liver, mesenteric white adipose tissue (MWAT), brain, and aorta flavanol metabolites from standard chow-diet-fed (ST) and cafeteria-diet-fed (CAF) rats were analyzed by high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) 21 h after the last 12-week-daily GSPE (100 mg/kg) dosage. Results showed that long-term GSPE intake did not trigger a flavanol tissue accumulation, indicating a clearance of products at each daily dosage. Therefore, results suggest that polyphenol benefits in a disease state would be due to a daily pulsatile effect. Moreover, obesity induced by diet also influences the metabolism and bioavailability of flavanols in rats.

Novel application of brain-targeting polyphenol compounds in sleep deprivation-induced cognitive dysfunction.

Sleep deprivation produces deficits in hippocampal synaptic plasticity and hippocampal-dependent memory storage. Recent evidence suggests that sleep deprivation disrupts memory consolidation through multiple mechanisms, including the down-regulation of the cAMP-response element-binding protein (CREB) and of mammalian target of rapamycin (mTOR) signaling. In this study, we tested the effects of a Bioactive Dietary Polyphenol Preparation (BDPP), comprised of grape seed polyphenol extract, Concord grape juice, and resveratrol, on the attenuation of sleep deprivation-induced cognitive impairment. We found that BDPP significantly improves sleep deprivation-induced contextual memory deficits, possibly through the activation of CREB and mTOR signaling pathways. We also identified brain-available polyphenol metabolites from BDPP, among which quercetin-3-O-glucuronide activates CREB signaling and malvidin-3-O-glucoside activates mTOR signaling. In combination, quercetin and malvidin-glucoside significantly attenuated sleep deprivation-induced cognitive impairment in -a mouse model of acute sleep deprivation. Our data suggests the feasibility of using select brain-targeting polyphenol compounds derived from BDPP as potential therapeutic agents in promoting resilience against sleep deprivation-induced cognitive dysfunction.

Synthesis and quantitative analysis of plasma-targeted metabolites of catechin and epicatechin.

Grape seed polyphenolic extract (GSPE) rich in the flavan-3-ols (+)-catechin and (-)-epicatechin beneficially modulates Alzheimer's Disease phenotypes in animal models. The parent molecules in the extract are converted to a series of methylated and glucuronidated derivatives. To fully characterize these metabolites and establish a robust quantitative assay of their levels in biological fluids, we have implemented a partial synthetic approach utilizing chemical methylation followed by enzymatic glucuronidation. Liquid chromatography/time-of-flight mass spectrometry (LC-TOF-MS) and nuclear magnetic resonance (NMR) spectroscopy were used to assign unequivocal structures to the compounds. An analytical method using solid-phase extraction and LC-MS/MS in selective reaction monitoring mode (SRM) was validated for their quantitation in plasma. These studies provide a basis for improvements in future work on the bioavailability, metabolism, and mechanism of action of metabolites derived from dietary flavan-3-ols in a range of interventions.

A grape seed extract increases active glucagon-like peptide-1 levels after an oral glucose load in rats.

We have previously reported that procyanidins, a class of flavonoids, improve glycemia and exert an incretin-like effect, which was linked to their proven inhibitory effect on the dipeptidyl-peptidase 4 (DPP4) activity. However, their actual effect on incretin levels has not been reported yet. Therefore, in the present study we have evaluated whether a grape seed extract enriched in procyanidins (GSPE) modulates plasma incretin levels and attempted to determine the mechanisms involved. An acute GSPE treatment in healthy Wistar female rats prior to an oral glucose load induced an increase in plasma active glucagon-like peptide-1 (GLP-1), which was accompanied by an increase in the plasma insulin/glucose ratio and a simultaneous decrease in glucose levels. In agreement with our previous studies, the intestinal DPP4 activity was inhibited by the GSPE treatment. We have also assayed in vitro whether this inhibition occurs in inner intestinal tissues close to GLP-1-producing cells, such as the endothelium of the capillaries. We have found that the main compounds absorbed by intestinal CaCo-2 cells after an acute treatment with GSPE are catechin, epicatechin, B2 dimer and gallic acid, and that they inhibit the DPP4 activity in endothelial HUVEC cells in an additive way. Moreover, an increase in plasma total GLP-1 levels was found, suggesting an increase in GLP-1 secretion. In conclusion, our results show that GSPE improves glycemia through its action on GLP-1 secretion and on the inhibition of the inner intestinal DPP4 activity, leading to an increase in active GLP-1 levels, which, in turn, may affect the insulin release.

Target identification of grape seed extract in colorectal cancer using drug affinity responsive target stability (DARTS) technique: role of endoplasmic reticulum stress response proteins.

Various natural agents, including grape seed extract (GSE), have shown considerable chemopreventive and anti-cancer efficacy against different cancers in pre-clinical studies; however, their specific protein targets are largely unknown and thus, their clinical usefulness is marred by limited scientific evidences about their direct cellular targets. Accordingly, herein, employing, for the first time, the recently developed drug affinity responsive target stability (DARTS) technique, we aimed to profile the potential protein targets of GSE in human colorectal cancer (CRC) cells. Unlike other methods, which can cause chemical alteration of the drug components to allow for detection, this approach relies on the fact that a drug bound protein may become less susceptible to proteolysis and hence the enriched proteins can be detected by Mass Spectroscopy methods. Our results, utilizing the DARTS technique followed by examination of the spectral output by LC/MS and the MASCOT data, revealed that GSE targets endoplasmic reticulum (ER) stress response proteins resulting in overall down regulation of proteins involved in translation and that GSE also causes oxidative protein modifications, specifically on methionine amino acids residues on its protein targets. Corroborating these findings, mechanistic studies revealed that GSE indeed caused ER stress and strongly inhibited PI3k-Akt-mTOR pathway for its biological effects in CRC cells. Furthermore, bioenergetics studies indicated that GSE also interferes with glycolysis and mitochondrial metabolism in CRC cells. Together, the present study identifying GSE molecular targets in CRC cells, combined with its efficacy in vast pre-clinical CRC models, further supports its usefulness for CRC prevention and treatment.

The polyphenol-rich extracts from black chokeberry and grape seeds impair changes in the platelet adhesion and aggregation induced by a model of hyperhomocysteinemia.

OBJECTIVE: The mechanism action of the polyphenol-rich extracts from berries of Aronia melanocarpa (black chokeberry) and from grape seeds in the defence against homocysteine (Hcy) and its derivatives action in blood platelets is still unknown. In this study, the influence of the aronia extract and grape seeds extract (GSE) on the platelet adhesion to collagen and fibrinogen and the platelet aggregation during a model of hyperhomocysteinemia was investigated. The aim of our study in vitro was also to investigate superoxide anion radicals (O2⁻•) production after incubation of platelets with Hcy, HTL and the aronia extract and GSE during a model of hyperhomocysteinemia (induced by reduced form of homocysteine at final dose of 100 µM) and the most reactive form of Hcy--its cyclic thioester, homocysteine thiolactone (HTL, 1 µM). Moreover, the additional aim of our study was also to establish and compare the influence of the aronia extract, GSE and resveratrol (3,4',5-trihydroxystilben), a phenolic compound, which has been supposed to be beneficial for the prevention of cardiovascular events, on selected steps of platelet activation. METHODS: The effects of tested extracts on adhesion of blood platelets to collagen and fibrinogen were determined according to Tuszynski and Murphy. The platelet aggregation was determined by turbidimetry method using a Chrono-log Lumi-aggregometer. RESULTS: We have observed that HTL, like its precursor-Hcy stimulated the generation of O2⁻• (measured by the superoxide dismutase-inhibitable reduction of cytochrome c) in platelets and caused an augmentation of the platelet adhesion and aggregation induced by the strong physiological agonist-thrombin. Our present results in vitro also demonstrated that the aronia extract and grape seeds extract reduced the toxicity action of Hcy and HTL on blood platelet adhesion to collagen and fibrinogen, the platelet aggregation and superoxide anion radicals production in platelets, suggesting its potential protective effects on hemostasis during hyperhomocysteinemia. CONCLUSION: In the comparative studies, the aronia extract was found to be more effective antiplatelet factors, than GSE or resveratrol during a model of hyperhomocysteinemia. It gives hopes for development of diet supplements, which may be important during hyperhomocysteinemia.

In vitro fermentation of grape seed flavan-3-ol fractions by human faecal microbiota: changes in microbial groups and phenolic metabolites.

With the aim of investigating the potential of flavan-3-ols to influence the growth of intestinal bacterial groups, we have carried out the in vitro fermentation, with human faecal microbiota, of two purified fractions from grape seed extract (GSE): GSE-M (70% monomers and 28% procyanidins) and GSE-O (21% monomers and 78% procyanidins). Samples were collected at 0, 5, 10, 24, 30 and 48 h of fermentation for bacterial enumeration by fluorescent in situ hybridization and for analysis of phenolic metabolites. Both GSE-M and GSE-O fractions promoted growth of Lactobacillus/Enterococcus and decrease in the Clostridium histolyticum group during fermentation, although the effects were only statistically significant with GSE-M for Lactobacillus/Enterococcus (at 5 and 10 h of fermentation) and GSE-O for C. histolyticum (at 10 h of fermentation). Main changes in polyphenol catabolism also occurred during the first 10 h of fermentation; however, no significant correlation coefficients (P > 0.05) were found between changes in microbial populations and precursor flavan-3-ols or microbial metabolites. Together, these data suggest that the flavan-3-ol profile of a particular food source could affect the microbiota composition and its catabolic activity, inducing changes that could in turn affect the bioavailability and potential bioactivity of these compounds.

Effect of dietary grape seed extract and Cistus ladanifer L. in combination with vegetable oil supplementation on lamb meat quality.

Thirty-six Merino Branco lambs were assigned to six dietary treatments: control diet (C) consisting of 90% dehydrated lucerne and 10% wheat bran; C with 6% of oil blend (CO); C with 2.5% of grape seed extract (GS); GS with 6% of oil blend (GSO); C with 25% of Cistus ladanifer (CL), and CL with 6% of oil blend (CLO). Meat lipid and colour stability was then evaluated during 7 days of storage. The effect of inclusion of grape seed extract and C. ladanifer in diets on meat sensory properties was also evaluated. Meat antioxidant potential, determined after oxidation induction by a ferrous/hydrogen peroxide system, decreased with oil supplementation (P<0.001), but inclusion of grape seed extract and C. ladanifer in diets protected the meat against lipid oxidation (P=0.036). Meat colour was not affected by diets. Inclusion of grape seed extract and C. ladanifer in diets did not change the sensory properties of meat.

Ascorbic acid offsets the inhibitory effect of bioactive dietary polyphenolic compounds on transepithelial iron transport in Caco-2 intestinal cells.

We previously reported that (-)-epigallocatechin-3-gallate (EGCG) and grape seed extract (GSE) at high concentration nearly blocked intestinal iron transport across the enterocyte. In this study, we aimed to determine whether small amounts of EGCG, GSE, and green tea extract (GT) are capable of inhibiting iron absorption, to examine if ascorbic acid counteracts the inhibitory action of polyphenols on iron absorption, and to explore the mechanisms of polyphenol-mediated apical iron uptake and basolateral iron release. An(55)Fe absorption study was conducted by adding various concentrations of EGCG, GSE, and GT using Caco-2 intestinal cells. Polyphenols were found to inhibit the transepithelial (55)Fe transport in a dose-dependent manner. The addition of ascorbic acid offset the inhibitory effects of polyphenols on iron transport. Ascorbic acid modulated the transepithelial iron transport without changing the apical iron uptake and the expression of ferroportin-1 protein in the presence of EGCG. The polyphenol-mediated apical iron uptake was inhibited by membrane impermeable Fe(2+) chelators (P < 0.001), but at a low temperature (4°C), the apical iron uptake was still higher than the control values at 37°C (P < 0.001). These results suggest that polyphenols enhance the apical iron uptake partially by reducing the conversion of ferric to ferrous ions and possibly by increasing the uptake of polyphenol-iron complexes via the energy-independent pathway. The present results indicate that the inhibitory effects of dietary polyphenols on iron absorption can be offset by ascorbic acid. Further studies are needed to confirm the current findings in vivo.